Several proteins interact with elastin, an essential extracellular matrix element. We describe here an additional elastin-binding protein from the porcine kidney. This protein was extractable with an isotonic buffer, and was purified by a rapid and simple procedure employing its characteristic properties: high affinity for red A-agarose and spontaneous formation of cryoprecipitate. Immunohistochemical studies using antibody against the purified protein demonstrated its localization in the cytoplasm of proximal tubules of the normal rat kidney. On Western blotting using the antibody, an immunoreactive protein was detected in the liver as well as in the kidney. On the basis of the partial amino acid sequences of the purified protein, it was identified as argininosuccinate synthetase. Some biochemical properties of the protein were different from the data reporting a hepatic form of argininosuccinate synthetase, a key enzyme in the urea cycle in the liver. These results suggest that the elastin-binding property of a renal form of the enzyme may be related to a tissue-specific function in the kidney.